The advent of cloud-based computing architectures has opened new possibilities for the rapid and scalable deployment of virtual Web stores, media outlets, and other on-line sites or services. In general, a cloud-based architecture deploys a set of hosted resources such as processors, operating systems, software and other components that can be combined or strung together and provided to a client or an end user. Cloud computing is often provided “as a service” over the internet. Two distinct layers of such services in cloud computing can be in the form of the infrastructure as a service (IaaS) layer and the platform as a service (PaaS) layer.
The PaaS layer is a combination of a development platform and a set of software subsystems or components that may be used to deliver a fully functional product or service. It provides a platform on which software developers may build new applications or extend existing ones without the complexity of owning and managing the underlying hardware and software and provisioning hosting capabilities. In other words, the PaaS layer provides the supporting platform to enable the end user develop his or her own solutions.
The IaaS layer delivers computer infrastructure, including a virtualization environment, as a service. This may include servers, software, data-center space and network equipment, available in a single bundle and may be billed as per usage in a utility computing model. IaaS may generally be used by organizations that have the in-house expertise to manage their IT requirements but may not have the infrastructure. They may hire the infrastructure from IaaS providers and load up their libraries, applications, and data, after which they may configure them themselves.